Targeted at learning about inflammatory eye diseases, this project focused in fiscal year 1997 on mechanisms of physiological immunotolerance toward self ocular antigens and pathogenic processes provoked in the eye by lymphoid cells that recognize these antigens. The major achievements of this year include the following: 1) Unlike normal wildtype mice, that are tolerant to their self lens crystallins, mice deficient in alphaB-crystallin due to genetic manipulation (knockout mice) recognized the deleted crystallin as "non-self" and developed vigorous immune response against it. Moreover, lymphocytes from the immunized knockout mice produced ocular inflammation when adoptively transferred into naive wildtype controls. This newly described experimental disease presents a novel animal model for lens-associated inflammatory eye disease. The alphaB-crystallin knockout mice also differ from the alphaA- crystallin knockout mice that are immunotolerant against the deleted crystallin (see our Annual Report of 1996). The new finding thus supports our assumption that the deletion of alphaA-crystallin was incomplete and a remnant portion of the molecule was sufficient to retain the state of tolerance against the whole self alphaA- crystallin. (2) The immunopathogenic capacity of lymphocytes with specificity toward ocular antigens was investigated using a line of transgenic mice in which the T-cell receptor (TCR) on the majority of lymphocytes is specific against hen egg lysozyme (HEL). Lymphocytes of these mice were adoptively transferred into mice of another transgenic line, that express HEL in their lens. Only mild inflammatory changes, if any, were seen in eyes of recipient mice injected with unstimulated ("naive") lymphocytes. On the other hand, severe ocular inflammation developed when the transferred cells were previously stimulated in culture with HEL. These results thus underscore the importance of lymphocyte activation in the inflammation-inducing process and the system provides a new tool to investigate the features of disease-inducing lymphocytes. The immunopathogenicity of the HEL-specific lymphocytes was further tested by mating the two lines of transgenic mice. Double transgenic mice developed severe inflammatory changes in their eyes, similar to those seen in the recipients of stimulated lymphocytes. The ocular disease in the double transgenic mice provides a new experimental system to investigate immunopathogenic processes against lens-specific antigen.